California’s election on Tuesday could play a more decisive role in this year’s Democratic presidential primary than it has in decades — and if you’ve been procrastinating on paying attention, there’s still time to make your voice heard.

More than a dozen states will vote on Super Tuesday, and California is the biggest prize on the map, with 415 pledged delegates at stake. The time in the spotlight comes just as the field of White House contenders is in flux, with former Vice President Joe Biden seeing momentum from his huge South Carolina win on Saturday, former South Bend, Indiana, Mayor Pete Buttigieg and Sen. Amy Klobuchar dropping out of the race, and Sen. Bernie Sanders trying to hold onto his lead in California.

Polls are open tomorrow from 7 a.m. to 8 p.m. Thanks to a new state law, you can still register to vote or change your party registration today or on Election Day.

If you received a vote-by-mail ballot, you can also mail it in still — as long as it’s postmarked by Tuesday and it arrives at your county elections office by Friday, your vote will be counted. You can also drop it off at your polling place, vote center, or county elections office.

One important note: If you’ve already cast your vote for a candidate who’s since dropped out of the race, like Buttigieg, Klobuchar, former San Francisco hedge fund chief Tom Steyer, or entrepreneur Andrew Yang, you can’t get a do-over. Casting a new ballot for a different candidate could violate state law against voting twice.

If you’ve already filled out your ballot for Buttigieg or another candidate but haven’t sent it in yet, you can surrender the ballot at your polling place or voting center and get a new blank one.

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And if you’re a no party preference voter who received a ballot in the mail without any presidential candidates on it, don’t send that back in if you want to have a say in the Democratic primary. You have to go to your polling place, vote center, or county elections office and exchange it for a Democratic crossover ballot.

Registered Republicans or members of other parties can’t participate in the Democratic primary — but they can change their registration to Democrat or no party preference and then cast a vote in the primary if they want to.

As of Sunday night, more than 1.4 million Democratic ballots had been returned to elections officials — about 20 percent of the mail-in ballots sent out — according to data from Political Data Inc., a state political firm.

Casey Tolan covers national politics and the Trump administration for the Bay Area News Group. Previously, he was a reporter for the news website Fusion, where he covered criminal justice, immigration, and politics. His reporting has also been published in CNN, Slate, the Village Voice, the Texas Observer, the Daily Beast and other news outlets. Casey grew up in Milwaukee, Wisconsin and graduated from Columbia University.